I develop software for virtual racing league, which will download real weather to the game. Maybe it will be used by people who are owning their own API key. There should be an option to check at the start of "injector" ,if the key is entered correctly. There is exist some simple query that is possible to sent from program to your server to confirm that the specified key is valid? Or is it necessary to send whole regular http request and wait, if some error will returned?